Details

Autor(en) / Beteiligte

• Pardo Pérez, Laura C.
• Chalkley, Zora
• Wendt, Robert
• Ahmet, Ibbi Y.
• Wollgarten, Markus
• Mayer, Matthew T.

Titel

CO 2 electroreduction activity and dynamic structural evolution of in situ reduced nickel-indium mixed oxides

Ist Teil von

• Journal of materials chemistry. A, Materials for energy and sustainability, 2022-10, Vol.10 (38), p.20593-20605

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In the field of CO 2 electroreduction (CO 2 ER), tuning the selectivity among diverse products remains a major challenge. Mixed metal catalysts offer possible synergetic effects which can be exploited for tuning product selectivity. We present a simple wet chemical approach to synthesize a range of nickel-indium mixed oxide (Ni A In B Ox) thin films with homogeneous metal distribution. CO 2 electroreduction results indicate that the Ni A In B Ox mixed oxide thin films can achieve high CO selectivity (>70%) in contrast with the single metal oxides NiO (H 2 >90%) and In 2 O 3 (formate >80%). The relative composition Ni 40 In 60 Ox attained the best CO selectivity of 71% at moderate cathodic bias of −0.8 V RHE , while a higher cathodic bias ( E < −0.9 V) promoted a decrease of CO in favor of formate. A detailed investigation of the Ni 40 In 60 Ox thin films following progressive stages of reduction during CO 2 ER revealed dynamic structural transformations strongly dependent on applied bias and electrolysis time. For the CO-selective catalyst composition, at moderate cathodic bias ( E < −0.8 V) and short electrolysis times (1 h), the catalyst is composed of nickel-indium alloy grains embedded in amorphous Ni–In mixed oxide as observed by electron microscopy. Extending electrolysis time at −0.8 V for 10 h, or increasing the applied reductive bias to −1.0 V, result in a complete reduction of the residual oxide film into an interconnected array of multicomponent (In, Ni, Ni 3 In 7 ) nanoparticles which display significantly lower CO selectivity (<50%). Our results indicate that the persistent amorphous NiInOx oxide/alloy composite material preserved in the early stages of reduction at −0.8 V plays a key role in CO selectivity. The highly dynamic structure observed in this catalytic system demonstrates the importance of conducting detailed structural characterization at various applied potentials to understand the impact of structural changes on the observed CO 2 ER selectivity trends; and thus be able to distinguish structural effects from mechanistic effects triggered by increasing the reductive bias.